1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- 2 * vim: set ts=8 sts=4 et sw=4 tw=99: 3 * This Source Code Form is subject to the terms of the Mozilla Public 4 * License, v. 2.0. If a copy of the MPL was not distributed with this 5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ 6 7 #ifndef jsdtoa_h 8 #define jsdtoa_h 9 10 /* 11 * Public interface to portable double-precision floating point to string 12 * and back conversion package. 13 */ 14 15 #include <stddef.h> 16 17 struct DtoaState; 18 19 namespace js { 20 21 extern DtoaState* 22 NewDtoaState(); 23 24 extern void 25 DestroyDtoaState(DtoaState* state); 26 27 } // namespace js 28 29 /* 30 * js_strtod_harder() returns as a double-precision floating-point number the 31 * value represented by the character string pointed to by s00. The string is 32 * scanned up to the first unrecognized character. 33 * 34 * If se is not nullptr, *se receives a pointer to the character terminating 35 * the scan. If no number can be formed, *se receives a pointer to the first 36 * unparseable character in s00, and zero is returned. 37 * 38 * On overflow, this function returns infinity and does not indicate an error. 39 * 40 * *err is set to zero on success; it's set to JS_DTOA_ENOMEM on memory failure. 41 */ 42 #define JS_DTOA_ENOMEM 2 43 double 44 js_strtod_harder(DtoaState* state, const char* s00, char** se, int* err); 45 46 /* 47 * Modes for converting floating-point numbers to strings. 48 * 49 * Some of the modes can round-trip; this means that if the number is converted to 50 * a string using one of these mode and then converted back to a number, the result 51 * will be identical to the original number (except that, due to ECMA, -0 will get converted 52 * to +0). These round-trip modes return the minimum number of significand digits that 53 * permit the round trip. 54 * 55 * Some of the modes take an integer parameter <precision>. 56 */ 57 /* NB: Keep this in sync with number_constants[]. */ 58 typedef enum JSDToStrMode { 59 DTOSTR_STANDARD, /* Either fixed or exponential format; round-trip */ 60 DTOSTR_STANDARD_EXPONENTIAL, /* Always exponential format; round-trip */ 61 DTOSTR_FIXED, /* Round to <precision> digits after the decimal point; exponential if number is large */ 62 DTOSTR_EXPONENTIAL, /* Always exponential format; <precision> significant digits */ 63 DTOSTR_PRECISION /* Either fixed or exponential format; <precision> significant digits */ 64 } JSDToStrMode; 65 66 67 /* Maximum number of characters (including trailing null) that a DTOSTR_STANDARD or DTOSTR_STANDARD_EXPONENTIAL 68 * conversion can produce. This maximum is reached for a number like -0.0000012345678901234567. */ 69 #define DTOSTR_STANDARD_BUFFER_SIZE 26 70 71 /* Maximum number of characters (including trailing null) that one of the other conversions 72 * can produce. This maximum is reached for TO_FIXED, which can generate up to 21 digits before the decimal point. */ 73 #define DTOSTR_VARIABLE_BUFFER_SIZE(precision) ((precision)+24 > DTOSTR_STANDARD_BUFFER_SIZE ? (precision)+24 : DTOSTR_STANDARD_BUFFER_SIZE) 74 75 /* 76 * DO NOT USE THIS FUNCTION IF YOU CAN AVOID IT. js::NumberToCString() is a 77 * better function to use. 78 * 79 * Convert dval according to the given mode and return a pointer to the 80 * resulting ASCII string. If mode == DTOSTR_STANDARD and precision == 0 it's 81 * equivalent to ToString() as specified by ECMA-262-5 section 9.8.1, but it 82 * doesn't handle integers specially so should be avoided in that case (that's 83 * why js::NumberToCString() is better). 84 * 85 * The result is held somewhere in buffer, but not necessarily at the 86 * beginning. The size of buffer is given in bufferSize, and must be at least 87 * as large as given by the above macros. 88 * 89 * Return nullptr if out of memory. 90 */ 91 char* 92 js_dtostr(DtoaState* state, char* buffer, size_t bufferSize, JSDToStrMode mode, int precision, 93 double dval); 94 95 /* 96 * DO NOT USE THIS FUNCTION IF YOU CAN AVOID IT. js::NumberToCString() is a 97 * better function to use. 98 * 99 * Convert d to a string in the given base. The integral part of d will be 100 * printed exactly in that base, regardless of how large it is, because there 101 * is no exponential notation for non-base-ten numbers. The fractional part 102 * will be rounded to as few digits as possible while still preserving the 103 * round-trip property (analogous to that of printing decimal numbers). In 104 * other words, if one were to read the resulting string in via a hypothetical 105 * base-number-reading routine that rounds to the nearest IEEE double (and to 106 * an even significand if there are two equally near doubles), then the result 107 * would equal d (except for -0.0, which converts to "0", and NaN, which is 108 * not equal to itself). 109 * 110 * Return nullptr if out of memory. If the result is not nullptr, it must be 111 * released via js_free(). 112 */ 113 char* 114 js_dtobasestr(DtoaState* state, int base, double d); 115 116 #endif /* jsdtoa_h */ 117